2022-05-28

for i in {1..100}
do
        ping -c1 -W1 -i0.2 $prefix$i > /dev/null
        if [ $? -eq 0 ]
        then
                echo $prefix$i
                nc -w 1 -vz $prefix$i 1-1056 2>&1 | grep succeeded
        fi
done

2020-08-15

Windows cmd ping sweep

Instead of installing a third party application which has the possibility to have spyware or other bad stuff in it. If you only need to do a ping sweep with no additional features it's probably easier just to do it in CMD.

Open up cmd
Run the following

for /L %z in (1,1,254) do @ping 10.0.0.%z -w 10 -n 1 | find "Reply"

Where:

(1,1,254) indicates to test every address from 1-254
10.0.0. is the network address prefix of addresses you want to test
%z is filled in with numbers from (1,1,254)
-w 10 - only waits 10ms before moving on
-n 1 - only tries once before moving on
find "Reply" looks for a succesful ping result and ignores unsuccessful

2015-12-07

Clean Console Log Output

To remove colour codes and redraw characters from console to make console logs more readable.



#!/usr/bin/env perl

while (<>) {

    s/ \e[ #%()*+\-.\/]. |

       (?:\e\[|\x9b) [ -?]* [@-~] | # CSI ... Cmd

       (?:\e\]|\x9d) .*? (?:\e\\|[\a\x9c]) | # OSC ... (ST|BEL)

       (?:\e[P^_]|[\x90\x9e\x9f]) .*? (?:\e\\|\x9c) | # (DCS|PM|APC) ... ST

       \e.|[\x80-\x9f] //xg;

    print;

}

Usage:



less /path/to/console.log | cleanLog | less

2015-07-21

Limiting Bandwidth Using Robocopy

Robocopy does not have any built in bandwidth limiter by rate specifically.

But what you can do is use the inner packet gap switch /ipg:n to simulate a lower bandwidth by adding more delay between packets.

The equation to use to calculate is as follows:

Where
D is the calculated latency or inner packet gap
Bd is the desired bandwidth you would like to transfer at
Ba is the available bandwidth to you

Example:
If my
Bd is 200kbps
Ba is 1000kbps



D=((1000-200)/(1000*200))*512*1000=2048

Therefore my /ipg:n will be /ipg:2048

References:
h ttps://yellowtriangle.wordpress.com/2012/06/28/bandwidth-throttling-with-robocopy/
http://www.zeda.nl/index.php/en/copy-files-on-slow-links
https://technet.microsoft.com/en-us/library/cc733145.aspx

2015-07-11

Sourcing Files in Bash

I never quite understood why when you changed .bashrc you had to type the source command in order to make changes active.

Now I understand and it's fairly straight forward.

Your current bash environment is defined by a PID that can be found using



echo $$

Any newly spawned bash processes for scripts will fork off of that process and be given a new process ID.

All variables for that newly spawned process will be local to that newly forked process.

If you would like the variables that would typically be local to your forked script to be active in your current shell you can use the source command in order to make them local to your current shell.

This acts in the same way when you would like to make variables in the .bashrc script local to your current shell. When the computer boots it runs .bashrc and puts variables in your current shell. If you would like to make any variable changes to re-read into your current shell. Similarly to how you would make variables to a remote script available to your local shell by using the source command you can do the same for .bashrc

Example:



source script.sh

The above will make all variables in script.sh available to your local shell at echo $$



source .bashrc

The above will make all variables in script .bashrc available to your local shell at echo $$

2015-04-29

Create Redhat Syncronized Repo with Reposync

Prerequisites

Server registered with the appropriate version of RedHat
HTTP/FTP server to host repo files

Instructions

Install required components for managing yum repositories and createrepo utility for building new repo indexes.



yum install yum-utils createrepo



rhn_register



subscription-manager register --username $username  --password $password --auto-attach

Repos will be populated automatically upon registration and you can then list them using:



subscription-manager repos --list

Download the repos to a path of your chosing



reposync --gpgcheck -l --repoid=$repoid --download_path=$path

Create the repo against the directory where your rpm packages exist



cd $path

createrepo $path

Enable the local repo



vi /etc/yum.repos.d/rhel.repo



[rhel-repo]

name=Red Hat Enterprise Linux 7 - x86_64

baseurl=http://$server/$path

enabled=1

gpgcheck=0

Ensure the repo works, this will likely build the index at the same time. I've seen elsewhere where cache is refreshed using yum makecache but I haven't run into a scenario where I have to do that yet.



yum repolist

References:
https://access.redhat.com/solutions/23016
http://kb.kristianreese.com/?View=entry&EntryID=77

Nerdy Notes

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